Sequential booster immunization means vaccination with a vaccine of a different route from the basic immunization vaccine. Sequential booster vaccination refers to vaccination using a vaccine of a different technical route from the basic immunization. For example, if two doses of the inactivated New Crown vaccine have already been administered, the recombinant protein vaccine from Chifironkoma or the adenovirus vector vaccine from Concinol can also be used for the sequential booster immunization. The use of sequential booster immunization allows complementary advantages between different vaccines. If an individual has a different body type and may experience more side effects from a particular type of vaccine, the use of different technical routes of vaccination can avoid the side effects. Sequential booster vaccination has the same precautions as the previous vaccination, you need to take the initiative to inform the physician of your own physical state before vaccination, and the professional doctor will rule out the contraindications to vaccination, and you need to observe the vaccination for 30 minutes, and leave the vaccination on your own if there is no adverse reaction.